DE4041773A1 - Copolymers of bis:imidazole monomers and olefinic comonomers - useful for sepn. of noble metals, esp. platinum@, palladium@ and rhodium, from aq. soln., from one another and from heavy metals - Google Patents

Abstract

Copolymers (I) contg. bis-imidazole gps. are produced by copolymerisation of cpds. of formula (II) with ethene derivs. of formula R4R5C=CR6R7 (III). In (II), R1 = 1-3C alkyl (esp. Me), vinyl 3-6C alkenyl or Hal-substd. 2-6C alkenyl, R2 = vinyl, 3-6C alkenyl or Hal-substd. 2-6C alkenyl, R3 = H opt. Hal-substd. 1-6C alkyl, aryl (esp. Ph) or substd. aryl (esp. Ph substd. with one or more Hal and/or lower alkyl gps. esp. p-halophenyl or tolyl), R4 = 1-6C alkyl, COR8, COOR9 or CON(R1O)2 (with R8-R10 = 1-3C alkyl), aryl (esp. Ph), substd. aryl (pref. Hal- or lower alkyl-substd. Ph, esp. p-halophenyl or tolyl) or CN, R5-R7 = H or opt. Hal-substd. 1-3C alkyl. Also claimed are copolymers (I) and monomers (II). The process is pref. carried out as a soln., pptn. or suspension copolymerisation in the presence of radical initiators and pref. also di- or poly-functional crosslinkers with mol. ratio (II):(III) = (1:20)-(1:3). The copolymer obtd. is protonated or quaternised with lower alkyl gps. USE/ADVANTAGE - Used for the sepn. of Pt gp. metals esp. Pt and/or Pd, from aq. solns. by contacting the soln. with (I) under suitable conditions, (ii) for the sepn. of Pt gp. metals esp. Pt from Pd or Rh, Pd from Rh or Pt, and Pt, Pd and Rh from one another, by contacting aq. solns. of the metal mixts. with (I) pref. in stages under conditions such that only Pd is absorbed in stage 1 (pref. at pH 0-1) and Pt is absorbed in stage 2 (pref. pH at least 2.5, esp. pref. 2.5-7) using fresh polymer (I), after which the sepd. metals and the Rh remaining in the soln. are isolated and (iii) for the sepn. of noble metals esp. Pt and/or Pd, from heavy metals esp. Pb, Hg, Cd and/or Ni, by contacting aq. solns. of the metals with (I) at pH 0-4 pref. 0-2 and sepg. the noble metal-loaded copolymer from the soln.

Description

The invention relates to a method for Her position of copolymers containing bisimidazole groups, the Co obtainable by the process according to the invention polymeric, new bisimidazole compounds, usable as Intermediates for the preparation of the copolymers and the Application of the obtained according to the inventive method copolymers for the separation of platinum group metals from aqueous solutions and the use of this copoly mers for the separation of platinum group metals from one another.

The platinum group metals (ruthenium, osmium, rhodium, Iridium, Palladium and Platinum) are used in technology for used for many purposes, for example in electronics trotechnik, but especially in chemical engineering as Catalyst or catalyst component. A special one large amount is used for auto catalytic converters.

Auto catalytic converters often contain mixtures of Platinum group metals. Particularly supported catalysts, ins special monolith supported catalysts, the mixtures of Platinum and rhodium, platinum and palladium and mixtures of platinum, palladium and rhodium are used for used this application.

Both in the natural occurrences and in the technically applied products is the platinum group  metal content usually very low. Still is on because of the high price, the extraction is worthwhile.

The separation of the platinum group metals from each other is a due to their similar chemical behavior highly complicated process, which makes it even more difficult will that both in natural occurrences and at for example in catalysts the content and the proportion of different platinum group metals can fluctuate.

However, many of the known separation methods have Disadvantages, for example due to high operating costs when using expensive chemicals or through complex Process technology.

The use of organic polymers (ionex exchanger resins) which have basic groups and com plexing or chelating or, if the basic Groups in protonated or quaternized form gene, with the formation of ionic interactions It has certain advantages in absorbing metal ions split up. For example, those with platinum groups metal-loaded resins after use separate the aqueous solution. Since precipitant and Lö is not necessary, is a possible responsibility no need to worry about water purification.

The object of the invention was to provide new advantageous copolymers, applicable for the separation of platinum group metals from aqueous solutions and for the separation of platinum group metals from one another and for the separation of noble metals, in particular platinum and palladium, from heavy metals. This object is achieved by the copolymers obtainable by the process of the invention. The process according to the invention for the preparation of copolymers containing bisimidazole groups is characterized in that compounds of the general formula (I)
wherein
R¹ and R² can be the same or different and R¹ is alkyl with 1 to 3 C atoms, especially methyl, vinyl, linear or branched alkenyl with 3 to 6 C atoms, halogen-substituted alkenyl with 2 to 6 C atoms and R² Vinyl, linear or branched alkenyl having 3 to 6 carbon atoms, halogen-substituted alkenyl having 2 to 6 carbon atoms
R³ is hydrogen, linear or branched alkyl having 1 to 6 carbon atoms, alkyl substituted by halogen having 1 to 6 carbon atoms, aryl, in particular phenyl, substituted aryl, in particular phenyl, in particular p-halogen, substituted by halogen and / or lower alkyl groups phenyl, tolyl means
copolymerized with ethene derivatives of the general formula (II)

wherein
R⁴ alkyl having 1 to 6 C atoms, COR⁸, COOR⁹, CO (NR₂¹⁰), wherein R⁸, R⁹, R¹⁰ are lower alkyl having 1 to 3 C atoms; Aryl, in particular phenyl, substituted aryl, preferably phenyl substituted by halogen or lower alkyl, in particular p-halophenyl, tolyl or the radical CN,
R⁵, R⁶, R⁷ may be the same or different and are hydrogen, optionally substituted by halogen-substituted lower alkyl having 1 to 3 carbon atoms.

Compounds of the general type are preferably used Formula (I) in which R¹ and R² are the same or in which R¹ is methyl and R² has the meaning given above owns.

R 1 and R 2 are particularly preferably vinyl, or it means R¹ methyl and R² vinyl.

The rest R³ means in the connections of the general my formula (I) preferably linear or branched Alkyl with 1 to 3 carbon atoms, aryl, especially phenyl by one or two lower alkyl groups with one to three carbon atoms substituted phenyl or by one or two halogen atoms substituted phenyl, in particular p-chlorophenyl.

R³ particularly preferably denotes hydrogen, methyl, Ethyl, propyl or phenyl.

The preferred compound of formula (II) is used such compounds in which R⁵, R⁶ and R⁷ water mean fabric.

In the compounds of general formula (II) be R⁴ is preferably phenyl, or COOR⁹, where R⁹ is methyl or ethyl.

The copolymerization can be initiated in a known manner be, for example, by irradiation or addition of activators such as radical pictures. The radical initiation is very applicable. As a radi Kalbilder can be used connections are used, e.g. B. peroxides such as ammonium peroxodi  sulfate or azo compounds such. B. azodiisobutyric acid nitrile.

The process can be done without applying a solution be carried out by means. The connections of the general My formulas (I) and (II) are mixed and the poly merization triggered, e.g. B. by adding a radical picture. The polymer obtained is after the polymer sation crushed.

The polymerization is preferably carried out under application of diluents, for example in the form solution polymerization, precipitation polymerization or a suspension polymerization. When performing the starting compounds are dissolved as solution polymerization gene in a suitable solvent, initiates the poly merisation and the Co dissolved in the solvent falls polymer by adding a non-solvent. The pro product can be ground and washed. That kind of Polymerization is suitable, for example, for manufacturing provision of copolymers with aromatic groups. As Solvent is, for example, xylene, as Non-solvent water or alcohols like methanol.

The process according to the invention is preferably carried out in Form of a precipitation polymerization or a suspension polymerization by.

Triggers to carry out precipitation polymerization the starting compounds, in a solvent which the copolymer precipitates. For example, you solve the bisimidazole compound and acrylic acid ester in water and adds a radical picture. The copoly formed mer falls out of the water and can be separated and ge if necessary, be further processed.  

In the case of suspension polymerization, the Starting compounds in water with the addition of protection colloids as a dispersant. There can be common protective colloids are used, for example polysaccharides such as Starch, alginates or agar-agar, modified natural Polymers such as carboxymethyl, hydroxyethyl or methyl cellulose, or synthetic polymers such as polyvinyl alcohol fetch This type of polymerization is suitable for the type application to monomers that are insoluble in water, for example compounds containing aromatic groups gene of the general formula (II) such as styrene. It is formed Polymer particles that are separated and further processed can be.

The molar ratio of the compounds of the general Formula (I) and (II) is in the process according to the invention about 1:20 to 1: 3.

If desired, customary aids can be used set, for example crosslinkers with two or more wetting groups, e.g. B. bis-acrylates such as N, N-methylene bis (acrylamide), in an amount of up to 6% by weight for example 2 to 6 wt .-%, based on the total weight of the polymer.

The manufactured according to the inventive method If desired, copolymer can also be used as a cleaning agent ration be subjected, for example, with Wash water or lower alkyl alcohols such as methanol, dry and shred.

If desired, the copolymer produced can still by means of organic or, preferably, inorganic acids, especially hydrochloric acid, in the protonated Form to be transferred.  

If desired, the one produced according to the invention can be used Copolymer using conventional quaternizing agents, e.g. B. methyl iodide, methyl sulfate, benzyl chloride, etc. quar be ternized.

Another object of the invention are the after bisimidazole obtainable by the process according to the invention copolymers containing groups, their acid addition ver bonds and their quaternized with lower alkyl groups products.

Those obtainable by the process according to the invention Copolymers are suitable for use in a process for the separation of platinum group metals from aqueous solder solutions and for the separation of platinum group metals from one another at the.

These application methods can be used in common equipment tures can be carried out continuously or in batches. The application method is expediently carried out in one or more columns.

Such a column contains a fixed bed or fluidized bed or fluidized bed made of absorbent resin. The column ent also keeps an inlet and an outlet for the open working aqueous solution and suitable facilities like sieves that prevent resin particles from escaping from the Should prevent column.

Usually used in technical applications several such columns connected in series. Most of time one uses two or more columns, part of which Columns for metal absorption from the water to be treated solution flows through and the other part to the rain regeneration solution is flowed through. By alternating switching of the columns to absorption and then on regeneration and then again on absorption  etc., the application process can be carried out continuously be performed.

As mentioned above, after the inventions copolymers available according to the process or their Acid addition products for the separation of platinum groups metals from aqueous solutions can be used. Im he Process according to the invention for the separation of platinum Group metals, especially platinum and / or palladium A platinum group metal is brought from aqueous solutions ion-containing aqueous solution with an after the invent Bisimidazole groups obtainable according to the process according to the invention containing copolymer, its acid addition products or its quaternization products under conditions in contact which is the separation of the platinum group metals enables and wins the separated platinum groups metals.

Absorb the bisimidazole groups of the copolymers the platinum group metals, which have the oxidation number +2 or have +4 from the aqueous solution. Without one Explanation for this ability to absorb want, it is assumed that chelate complexes Imidazole groups and platinum group metal ions of Form oxidation level +2 or +4. Rhodium is in aqueous solution usually in the oxidation state +3 in front and is not separated. This makes it suitable Variant of the method according to the invention for use on platinum group metals with the oxidation state +2 or +4. The concentration of platinum group metal ions in the Solution can fluctuate in a wide range, e.g. B. from from a few milligrams to several grams per liter. This form of application is particularly well suited for removal platinum, palladium or platinum and palladium together from aqueous solutions.  

The pH of the aqueous solution can range from strong acidic and alkaline, for example between 0 and about 10 lie. It is preferred to work at a pH below of 7. Inorganic acidification is expediently used Acids, especially nitric acid or halogen water Substance acids such as hydrochloric acid.

The temperature can range from 5 to 80 ° C.

The duration of the contact until the desired Ab degree of sorption can be easily determined by means of orientation tests determine. If desired, you can use the separation process Repeat several times to the desired degree of absorption.

The regeneration of the resins loaded with metal ions is described below.

As already mentioned above, the inventions are suitable copolymers according to the invention also for use in a ver drive to separate platinum group metals from each other. In this inventive method for the separation of Platinum group metals, especially for the separation of Pla tin of palladium, for the separation of platinum from rhodium, for the separation of palladium from rhodium and for the separation of platinum, palladium and rhodium are brought together an aqueous solution containing platinum group metals with one obtainable by the process according to the invention, Copolymer containing bisimidazole groups under certain conditions contacts that enable separation, and ge wins the separated platinum group metals.

As the inventors surprisingly found rhodium, which is in the oxidation state +3, not absorbed. The method according to the invention The platinum group metals are suitable from one another half for the separation of platinum group metals from the oxides tion level +2 or +4 of rhodium of oxidation level +3.  It is suitable, for example, for separating platinum from Rhodium, from Palladium from Rhodium or Platinum and Palla dium together from rhodium. For separation, for example of platinum contacted by rhodium in aqueous solutions the solution with a Ver drive available copolymers and absorbs on them Selectively select the platinum. This can, as below is described, worked up for the production of platinum will. The aqueous solution only contains rhodium and can in a known manner on the extraction of rhodium be worked, for example by separating the Water and reduce the remaining rhodium salt. In the separation of palladium from follows in a completely analogous manner Rhodium or platinum and palladium together from rhodium.

The pH value can in turn be between strongly acidic and are alkaline. It is preferably in the range between about 0 and about 10. It is preferably between about 0 and about 7. The temperature at the separation is in Range between 5 and 80 ° C. The contact time or the Volume flow of the aqueous solution is adjusted so that the desired degree of absorption is achieved. Desired if you can the separation process to the desired Ab Repeat degree of sorption one or more times.

The use of copolymers of the general formula (I) but is also suitable in a separation process of platinum group metals with oxidation state +2 or +4 from each other. For example, you can platinum from palladium or separate platinum, palladium and rhodium. The inventors have surprisingly found that the copolymers of the invention not only rhodium not absorb, but that palladium and platinum differed be absorbed quickly. Palladium becomes very much absorbed faster than platinum. This effect can be by working at the lowest possible temperatures, e.g. B. between 5 and 20 ° C, and expediently by adjusting a strongly acidic pH, for example adjusting  increase the pH to about 0 or below. At such a low temperature and possibly a low pH essentially only palladium is absorbed. One therefore works to separate palladium from platinum with the shortest possible contact time, for example below a contact time of about 1 hour and / or less Temperature, for example between 5 and 20 ° C and / or at a pH value less than or equal to 0. That with absorber Palladium-loaded ion exchange resin is then of the aqueous solution called platinum group metal ions contains essentially only platinum ions, separated. This can be done, for example, by draining off the aqueous solution solution or by sieving the ion exchange resin from the used container happen.

The palladium absorbed in the ion exchange resin is processed as described below.

After the selective removal of the palladium ver remains an aqueous solution that, as I said, only Contains platinum ions. Now also the platinum content There are various ways of obtaining from the aqueous solution opportunities. For example, you can take the water off evaporate and the remaining residue on platinum work. However, the platinum is also preferably separated Use of the copolymers according to the invention from aqueous solution. To do this, contact the aqueous one Solution with fresh copolymer according to the invention, expediently ßig at a temperature above about 30 ° C, preferably point above about 40 ° C, and increases the pH above 0, preferably above 2.5, for example between about 2.5 and 7. Now the platinum from the copo lymer absorbed. The absorbed platinum is then re- Separating the copolymer from the aqueous solution such as worked up described below.  

The advantageous ones are particularly striking Properties of the copolymers according to the invention in the Ab separation of platinum, palladium and rhodium from each other. In this particularly advantageous embodiment is chosen the conditions for separation in a first step such that selectively only palladium is absorbed and separates the loaded copolymer. Then you give fresh Copolymer and then changes the conditions to that platinum is selectively absorbed. According to the selective Absorption of the palladium compound in the first step and the selective absorption of the platinum compound in the second step remains an aqueous solution that only still contains rhodium. The palladium, platinum or Rho dium compounds are then described in the Way won.

As conditions that are selective in the first step Allowing separation of palladium is to be mentioned contact time as short as possible, for example below about an hour, the lowest possible temperature, for example between 5 and 20 ° C in the solution, and / or a low pH of about 0 or below. The The copolymer is then selectively loaded with palladium Carrying out the 2nd stage of the aqueous solution, the still contains platinum and rhodium ions, separated.

If you work in a batch process, you can, for example reject the aqueous solution from the container, or one separates the copolymer from the solution by sieving, and gives fresh copolymer in to carry out the 2nd stage the solution.

If you work continuously, it is advisable to run it aqueous solution to carry out the 2nd stage on fresh Copolymer, for example by switching to a 2nd column.  

For the selective separation of platinum in the 2nd step then you change the conditions so that the Temperature increased, for example above about 20 ° C, preferably to above 30 ° C, and / or that the pH is increased, for example to about 2.5 to 7.

To obtain the Rho remaining in the solution You can use usual methods, for example you can evaporate the water and the remaining Rho Reduce dium connection.

To obtain the now separate, in You can use copolymer-absorbed palladium and platinum ions ash the loaded copolymer separately, for example. The remaining platinum group metals can be known Isolated from the residue of this ashing and be worked up.

The platinum group metals absorbed in the copolymer can also be obtained by regenerating the copolymers will. To do this, contact the loaded resins for example with highly concentrated acid, for example Hydrochloric acid, with strongly alkaline solutions, for example Sodium hydroxide solution, or with highly complexing compounds, for example with cyanide or thioureas. The de sorbed platinum group metal ions fall into the rain ration solution and are known from this Process isolated, for example by evaporating the Water and reducing to the appropriate platinum groups metal.

Those obtainable by the process according to the invention Copolymers are also particularly suitable for separation sere of platinum and palladium of base metals, ins special heavy metals such as lead, mercury, cadmium and nickel. To this end, he is contacted according to the invention available copolymers with an aqueous solution, the Precious metals, especially platinum and / or palladium as well  Base metals, especially heavy metals, such as lead, Contains mercury, cadmium, and / or nickel in one pH between 0 and about 4, preferably 0 and about 2, and separates the copolymer loaded with the noble metal. Copper does not become at a pH below about 2 absorbed. One can therefore according to the invention Processes precious or platinum group metals also from solution cut off the copper containing, if one at correspondingly low pH, e.g. B. between 0 and 1 ar works.

Furthermore, it is of course possible to selectively copper separate from aqueous solutions, the copper with others Contain non-metals, provided you have a pH of works about 2 or higher.

The loaded copolymer can then as described worked up to extract the copper or precious metal will.

Another object of the present invention are usable in the manufacturing process according to the invention Monomers of the general formula (III)

wherein
R¹¹ and R¹² may be the same or different and R¹¹ is alkyl with 1 to 3 C atoms, preferably methyl, vinyl, linear or branched alkenyl with 3 to 6 C atoms, halogen-substituted alkenyl with 2 to 6 C atoms and R¹² Means vinyl, linear or branched alkenyl with 3 to 6 C atoms, halogen-substituted alkenyl with 2 to 6 C atoms,
R¹³ is hydrogen, linear or branched alkyl having 1 to 6 carbon atoms, halogen-substituted alkyl having 1 to 6 carbon atoms aryl, in particular phenyl, substituted aryl, in particular substituted phenyl, preferably p-halophenyl, tolyl.

Monomers of the general formula (III) are preferred in which R¹¹ and R¹² are the same or in which R¹¹ Is methyl and R¹² has the meaning given above owns. Monomers of all are very particularly preferred mean formula (III) in which R¹¹ and R¹² mean vinyl ten or in which R¹¹ is methyl and R¹² is vinyl.

In the monomers of the general formula (III) meaning tet R¹³ is preferably hydrogen, methyl, ethyl, propyl or Phenyl.

Very particularly preferred monomers are bis (N-vinyl imidazol-2-yl) methylcarbinol, bis (N-vinylimidazol-2-yl) - phenylcarbinol and (N-methylimidazol-2-yl) (N-vinylimida zol-2-yl) carbinol.

The following are methods of making the Bisimidazole monomers of the general formula (III) be wrote.

According to a variant you can

• a) for the preparation of compounds of general Formula (III), in which R¹ and R² are the same, of Imi dazolen of the general formula (IV) R1 - H (IV) or  
• b) for the preparation of compounds of the general formula (III), in which R¹ and R² are different, from Ge mix imidazoles of the general formula (IV) and the general formula (V) starts R¹ - H (IV) R² - H (V)

wherein
H means hydrogen
the imidazole compound of the general formula (IV) used or the mixture of imidazole compounds of the general formula (IV) and (V) is converted into the corresponding imidazolyl-lithium compounds and 2 molar equivalents of this compound or 2 molar equivalents of a mixture of these compounds with 0, 9 to 1.1 molar equivalents of an ester of the general formula (VI)

R³ - C (O) OR (VI)

wherein
R³ has the meaning given above and R⁷ represents alkyl having 1 to 6 carbon atoms,
implemented, the intermediate reaction product with a protic compound, in particular water, hydrolyzed and the imidazole compound of the general formula (III) or the mixture of imidazole compounds of the general formula (III) from the reaction mixture.

Another method is also suitable for manufacturing position of compounds of general formula (III), in which R1 and R2 are the same. This method is suitable but especially for the production of such a connection in which R¹ and R² are not the same. With this  Procedures drop the corresponding connections with high Selectivity. This manufacturing process is ge indicates that an imidazole of the general formula (IV) converted into the imidazolyl lithium compound and 1 mole equivalent of this compound with 0.9 to 1.1 mole equi valents of a carboxamide of the formula R³-C (O) N (R⁸) ₂ implements, wherein R³ has the meaning given above sits and R⁸ for hydrogen or lower alkyl with 1 to 3 carbon atoms, the intermediate reak is formed tion product hydrolyzed, the imidazole R³-ketone formed or imidazole-R³-carbaldehyde isolated and this with 0.9 to 1.1 molar equivalents of one in the lithium compound converted imidazole compound of the general formula (IV) or (V) implements.

The implementation, at least that before proteolysis or Hydrolysis of the intermediate product formed process steps performed, is expediently under Aus conclusion of air humidity and oxygen. To this end, the measures known to the person skilled in the art can be taken be opened. How to implement the implementation in one closed apparatus under an inert gas atmosphere, for example under a nitrogen atmosphere. Adsorbed Traces of moisture can be removed from the apparatus by heating zen and applying a vacuum or passing a dry inert gas stream. Solution means become absolute in absolute (i.e. essentially what used).

When carrying out the implementation one takes care of purpose moderately for good mixing, for example by a magnetically operated stirrer.

The conversion of the imidazole compound into an imi dazolyl-lithium compound is used at very low temperatures doors carried out, advantageously below -60 ° C. Imidazolyl lithium compounds are quite insta bil. It is therefore recommended that you continue to do so  processing of the imidazolyl lithium compound prepared with the ester compound used or the car bonsäureamids the reaction mixture at a temperature keep below about -60 ° C. Only after complete addition of the ester or amide compound and one if desired, the post-reaction phase still carried out the temperature is allowed to rise.

The use of a solvent already in the Preparation of the imidazolyl lithium compound is recommended worth it. It is advisable to choose an aprotic, solvent inert to lithiating reagents from, advantageously at the depths used Temperatures is still fluid. Are very suitable for example aliphatic ethers, especially diethyl ether.

For the conversion of the imidazole compound into the Imidazolyl-lithium compound come usual lithiation reagents in question. Butyllithium is very suitable. It can be in the form of the commercial solution in n-hexane be set.

Imidazole compound and lithiation reagent, esp special butyllithium, are advantageous in the molar ratio of about 1: 1 implemented with each other. Since lithiation rea genien are very sensitive to hydrolysis, is the front previous determination of the effective content recommended. This can be done using known methods, for example by the method of H. Gilman, F.K. Cartledge in J. Organomet. Chem. 2 (1964), pages 447 to 454.

The imidazole compound, advantageously in one suitable solvents, for example diethyl ether, ge dissolves, is presented and cooled, expediently Temperatures below about -60 ° C. The lithiation reagent, preferably butyllithium in hexane, is added drips. The temperature in the reaction mixture should  do not rise above -60 ° C during the dropping. To when the addition is complete, the ester compound is added dropwise. they can be added in the form of a solution, this is however not necessary and also not advantageous. Imida zol compound and ester are, as already stated above provides, conveniently in a molar ratio of 2: 1 implemented each other. Even while adding the ester the temperature of the reaction mixture should always be below half of about -60 ° C. After the ester addition has ended can, if desired, carry out a post-reaction phase that can last up to a few hours. Also the temperature is during this post-reaction phase expediently below -60 ° C.

The reaction mixture is then slowly warmed up for example to a temperature between 0 and 20 ° C, and with a protic compound, e.g. B. a water mix baren aliphatic lower alkyl alcohol such as methanol or Ethanol, a corresponding alcohol-water mixture or, preferred, mixed with water or ice. The protic Compound or water is based on the used butyl lithium compound in molar excess set.

Occasionally, protolysis may already occur or hydrolysis the product precipitate as a solid. In In this case, the solid is first separated off.

The organic phase is separated from the aqueous phase separately, e.g. B. by decanting, and the organic phase concentrated to obtain the product.

For the production using carboxylic acid The same applies analogously to amides. Here is hydrolysis added hydrochloric acid and the ether phase with hydrochloric acid extracted and the extracts with sodium carbonate neutra lized.  

The yield can be increased if in the aqueous phase any dissolved amounts by extraction be obtained, for example with ethyl acetate.

The N-alkenylimidazoles required are commercially available products or in a known manner from imidazole and correspond The corresponding acetylene derivatives can be produced.

Example 1. Preparation of bis (N-vinylimidazole 2-yl) methyl carbinol 1.1. Equipment used

A 500 ml three-necked flask was used. The three-neck piston was equipped with a mechanical stirrer. A T-shaped connector was with a three-necked piston and a supply line for supplying nitrogen gas and thus prevented the entry of air and moisture speed. There was a dropping funnel on the three-necked flask Put on 100 ml volume.

Solvents were evacuated on a commercially available vaporizable rotary evaporator.

1.2. execution

The apparatus was used to remove traces of moisture heated and dry before carrying out the experiment Nitrogen gas passed through the apparatus. To The hydrolysis was carried out under one atmosphere sphere of dried nitrogen worked.

The factor determination of the used in the implementation n-Butyllithium dissolved in n-hexane was obtained after the Method by H. Gilman and F.K. Cartledge in J. Organomet. Chem. 2 (1964), pages 447 to 454. 10 ml a mixture obtainable by mixing 1 ml of Di bromethane and 9 ml of diethyl ether, with 3 ml of the butyl  lithium solution in n-hexane. The mixture became Gently stirred for 2 minutes with distilled water added and titrated with acid against phenolphthalein.

Another 3 ml of the butyllithium solution in n-hexane were added mixed with 10 ml of diethyl ether, with distilled Water hydrolyzes and again with acid Titrated phenolphthalein.

From the difference between those obtained in the two titrations The content of the butyllithium solution was calculated.

With passage of dried nitrogen, 15 g (0.16) mol of N-vinylimidazole (from Fluka) in 250 ml dried diethyl ether and the mixture to -60 ° C. cooled down. The white suspension became inside An equimolar amount of 1 hour with vigorous stirring n-Butyllithium added dropwise in n-hexane. During the closing dropwise the stirred mixture was cooled so that the Temperature did not rise above -60 ° C. It imagined yellowish reaction product. About this reaction product the ethyl acetate (molar ratio of Imida zol: ester = 2: 1) was added dropwise. After the addition was complete the reaction mixture within about 2 hours brought a temperature of about 0 ° C. To complete Reaction were reached after reaching this temperature 30 ml of the ester were added again. Subsequently was hydro by adding 30 ml of distilled water lysed. Product that may have failed during hydrolysis was filtered off and the ether phase on a rotary evaporator constricted. By shaking the aq phase with ethyl acetate, the yield could easily be be increased.

The cleaning was carried out by repeated recrystallization from isopropanol.
Yield: 21% of theory
Melting point: <350 ° C (decomposition)

Elemental analysis: C₁₂H₁₄N₄O (230.27)
calc .: C 62.59%, H 6.13%, N 24.33%;
Found: C 62.43%, H 6.15%, N 24.15%.

1 H-NMR spectrum: (300 MHz, dimethyl sulfoxide-d₂)
δ (ppm)
1.66 (s, 1H, C-OH); 1.88 (s, 3H, C-CH₃);
4.72 (dd, 2H, vinyl protons);
5.30 (dd, 2H, vinyl protons);
6.84 (d, 2H, imidazole protons);
7.25 (dd, 2H, vinyl protons);
7.62 (d, 2H; imidazole protons)

Example 2 Preparation of bis (N-vinylimidazole 2-yl) phenylcarbinol

The device and implementation corresponded to Example 1.

Approach:
0.16 mol of N-vinylimidazole
0.16 mol of n-butyllithium in the form of a
1.6 n-butyllithium solution in n-hexane
0.08 mol ethyl benzoate

The purification was carried out by repeated recrystallization from ethyl acetate.
Yield: 75% of theory
Melting point: 183 ° C

Elemental analysis: C₁₇H₁₆N₄O (292.34)
calc .: C 69.85%, H 5.52%, N 19.17%;
Found: C 68.34%, H 5.49%, N 18.51%.

1 H-NMR spectrum: (300 MHz, dimethyl sulfoxide-d₂)
δ (ppm)
1.79 (s, 1H, C-OH);
4.60 (dd, 2H, vinyl protons);
5.04 (dd, 2H, vinyl protons);
6.94, 7.24, 7.31 (m, 9H, 4 protons of the imidazole rings and 5 protons of the phenyl ring)

Example 3 Preparation of (N-methylimidazole 2-yl) (N-vinylimidazol-2-yl) carbinol 3.1. Preparation of N-methyl-2-imidazole carbaldehyde

The one used under 1.1. described apparatus.

13.2 g (0.16 mol) of N-methylimidole were dissolved in 150 ml of dry, oxygen-free diethyl ether in a stream of nitrogen and the mixture was cooled to -60.degree. 0.16 mol of n-butyllithium in the form of 100 ml of a corresponding n-butyllithium solution was slowly added dropwise to this solution. The reaction mixture was stirred at -60 ° C for 1 hour. Then 20 ml (0.24 mol) of freshly distilled dimethylformamide, dissolved in 16 ml of dried, acid-free diethyl ether, were added dropwise to the still cooled reaction mixture. The reaction mixture now obtained was stirred for about 14 hours, the temperature of the cooling base slowly rising to 0 ° C. Some crushed ice was added to the reaction mixture, followed by about 100 ml of 4 normal hydrochloric acid. The organic phase was separated and extracted twice with 20 ml of the 4 normal hydrochloric acid. The combined hydrochloric acid extracts were made slightly alkaline with sodium carbonate and then shaken out several times with chloroform. The combined chloroform phases were evaporated over sodium sulfate. A yellowish oil remained, which crystallized after some time in the refrigerator.
Yield: 6 g, corresponding to 34% of theory
Melting point: 34 ° C

The experiment was repeated several times.

The combined products were in the next reaction step (Example 3.2.) used.

3.2. Conversion of N-methylimidazole-2-carbaldehyde in (N-methylimidazol-2-yl) (N-vinylimidazol-2-yl) carbinol

The one used under 1.1. described apparatus.

15 g (0.16 mol) of N-vinylimidazole were dissolved in 100 ml of dried, oxygen-free diethyl ether and cooled to -60 ° C. in a nitrogen stream in the well-heated apparatus. A white suspension is formed. 0.16 mol of n-butyllithium in the form of 100 ml of an n-butyllithium solution in n-hexane was added dropwise to the white suspension over the course of one hour with vigorous stirring. After the addition was complete, stirring was continued for 1 hour. Then 17.6 g (0.16 mol) of the 3.1. prepared N-methylimidazole-2-carbaldehyde, dissolved in 80 ml of dried, oxygen-free diethyl ether. The reaction mixture was then brought to room temperature within 3 hours and then 30 ml of water were added. Failed product was suctioned off. The aqueous and the organic phase were separated and the organic phase was shaken twice with 20 ml of water each time. The combined aqueous phases were saturated with NaCl and shaken out several times with chloroform. The combined organic phases were dried over magnesium sulfate and the solvent was evaporated on a rotary evaporator. The crude product was recrystallized from ethyl acetate.
Yield: 6.02 g, corresponding to 55% of theory
Melting point: 182 ° C
IR spectrum (KBr compact): 1660 cm ^-1 (ν-C = C),
1500 cm ^-1 , 1305 cm ^-1 , 940 cm ^-1 (ν ring)

Example 4 Manufacture of ion exchange resins General test regulations 4.1. Polymerization technique A: precipitation polymerization

Approaches: (see Tab. 1)
0.3-2 g bis (N-vinylimidazol-2-yl) carbinol
4-6 g of freshly distilled acrylic acid ethyl ester
0.1 g of N, N'-methylenebisacrylamide
0.1 g azodiisobutyronitrile

The substances were dissolved in 50 ml of water and at 80 ° C heated up. After about 4 hours a yellowish, gummy product formed. This polymer consisted of individual small pearls that agglome into larger pieces were.

4.2. Polymerization technique B: suspension polymer station

Approaches: (see Tab. 1)
0.3-2 g (bis (N-vinylimidazol-2-yl) methylcar binol or bis (N-vinylimidazol-2-yl) phenyl carbinol
4-6 g of freshly distilled styrene
0.15 g azodiisobutyronitrile
0-0.3 g of N, N'-methylenebisacrylamide
1 g starch

The substances were dispersed in 80 ml of water on the Was heated to 80 ° C. The proportion of imidazole compound was tion based on the styrene used less than 16 wt .-%, so a fine-grained product, the part wise from pearl-shaped, partly from irregularly shaped ren particles was formed. Fraction of the share of the put imidazole compound based on the used Styrene more than 16 wt .-%, so the monomers were initially finely divided in the aqueous phase. With away progressing degree of polymerization stuck to form the pearls into a tough, yellowish mass that hardened to a fixed point after 6 hours. This Product was after drying in a drying cabinet in the mortar it crushed.

Table 1 shows information on the test series 4.1.1. until 4.1.5. and 4.2.1. until 4.2.5. manufactured Ion exchange resins compiled. In% by weight stated proportions of the components relate to the Total weight of the finished copolymer. The rest on 100% by weight forms acrylic acid (resins P (1) to P (5) or Styrene (resins P (6) to P (10), and optionally before existing impurities, e.g. B. water or solvent.  

Table 1

Composition of the ion exchange resins

Determination of the capacity or swelling capacity of the ion exchange resins produced a) Determination of the capacity

To determine the capacity of the synthesized ion exchange resins, a Pt ⁴⁺ and Pd ²⁺ solution (concentration of Pt ⁴⁺ : 500 mg / l, pH value: 2.5; concentration of Pd ²⁺ : 1000 mg / l , pH: 1) 500 mg of the corresponding resin was added, the slurry was stirred at 40 ° C. for 4 hours and then left to stand for a further 24 hours. The resin was then filtered off and the remaining concentration of the corresponding noble metal was determined by atomic absorption spectroscopy. The results are summarized in Table 2.

b) Determination of the swelling capacity of the synthesized ion exchange resins

The respective ion exchange resin was in 24 hours Water swelled. The swollen polymer was suctioned off sharply on a nutsche, balanced wet, dried in an oil pump vacuum at 80 ° C and again weighed. The results are also in the table 2 summarized.  

Table 2

Table 2 shows that copolymers of Ethyl acrylate and bis (N-vinylimidazol-2-yl) methylcarbinol and from styrene and bis (N-vinylimidazol-2-yl) phenylcarbinol the largest capacities for platinum group metals have. The palladium capacity is particularly high of the experiment 4.2.3. manufactured ion exchange resin P (8). This resin is one without a crosslinker produced polymer with high swelling capacity. It is believed, that due to the high swelling capacity and the resulting expansion of the polymer backbone an improved Ion exchange also possible inside the polymer is.

Example 5 Use of ion exchange resins according to the invention for the separation of Pt ⁴⁺ and Pd ²⁺ from aqueous solutions 5.1. Application for the separation of Pt ⁴⁺

General instructions: 40 ml of an aqueous solution containing Pt ⁴⁺ were placed in a flask, the pH was adjusted to 2.5, 500 mg of that in Example 4.2.4. prepared resin P (9) added and the flask contents stirred vigorously. Small samples of the aqueous solution were taken at regular intervals and the noble metal content was examined photometrically (photometer LPG 089 from Dr. Lange). The initial concentrations and the separation temperature of the test series 5.1.1. to 5.1.3. are listed below.

5.1.1.

Initial concentrations of the Pt ⁴⁺ solution: 344 mg / l
Separation temperature: 20 ° C

5.1.2.

Initial concentrations of the Pt ⁴⁺ solution: 433 mg / l
Separation temperature: 40 ° C

5.1.3.

Initial concentrations of the Pt ⁴⁺ solution: 131 mg / l
Separation temperature: 40 ° C

The time course of the ion exchange on the basis of the photometrically measured residual Pt ⁴⁺ concentration in the aqueous solution is shown in Table 3 and graphs 1 and 2 in FIG. 1.

As can be seen particularly clearly from graph 1 in FIG. 1, platinum is separated off faster at 40 ° C. than at 20 ° C.

5.2. Separation of Pd ²⁺

General instructions: 40 ml of an aqueous solution containing Pd ²⁺ were placed in a flask, the pH of the solution was adjusted to 1, 500 mg of that in Example 4.2.4. prepared resin P (9) added and the contents of the flask stirred vigorously. Small samples were taken at regular intervals and the precious metal content was again examined photometrically. The initial concentrations of Pd ²⁺ and the temperature during the separation in the test series 5.2.1. until 5.2.3. are listed below.

5.2.1.

Initial concentration of the Pd ²⁺ solution: 100 mg / l
Separation temperature: 20 ° C

5.2.2.

Initial concentration of the Pd ²⁺ solution: 100 mg / l
Separation temperature: 40 ° C

5.2.3.

Initial concentration of the Pd ²⁺ solution: 480 mg / l
Separation temperature: 40 ° C

The time course of the ion exchange on the basis of the photometrically measured residual concentration of Pd ²⁺ in the aqueous solution is shown in Table 4 and in graphs 3 and 4 of FIG. 1. As graph 3 in FIG. 1 in particular shows, palladium is separated at 40 ° C. much more quickly than platinum.

Table 3

Time course of the ion exchange

Table 4

Use of the resin P (9) for the separation of Pd ²⁺ from aqueous solution

Time course of the ion exchange

Example 6 Use of ion exchange resins according to the invention for the selective separation of Pd ²⁺ from aqueous solutions which contain Pt ⁴⁺ and Pd ²⁺

In examples 6.1. until 6.9. the suitability of ion exchange resins according to the invention for the selective separation of palladium from platinum and palladium-containing aqueous solutions with changing platinum or palladium content was investigated. For this purpose, hydrochloric acid solutions (concentration of hydrochloric acid: 1 mol / l) with different platinum or palladium contents were prepared. In each case 20 ml of the corresponding solution were mixed with 0.5 g of the in Example 4.2.4. prepared ion exchange resin P (9) was added and the suspension was then left to stand in the sealed flask for 3 days. The resin was then filtered off and the platinum or palladium content in the aqueous solution was examined by atomic absorption spectroscopy. Table 5 shows the concentrations of platinum and palladium before and after the addition of resin in the test series 6.1. until 6.9. compiled. The resulting mole fractions of Pt ⁴⁺ and Pd ²⁺ in the solution and in the absorber resin are summarized in Table 6.

Table 5

Concentration of Pt ⁴⁺ or Pd ²⁺ before and after adding resin in the aqueous solution

Table 6

Calculated mole fractions for Pt ⁴⁺ or Pd ²⁺ in the aqueous solution or in the resin

From the given numerical values of the mole fractions the selectivity coefficient Kd by plotting the Determine mole breaks in the exchange resin or in the solution. In the strongly acidic solution (pH: 0) the Selectivity coefficient for platinum at 0.0078 and the Selectivity coefficient for palladium calculated to be 127. The selectivity coefficient for palladium is 127 in this very acidic solution is very large, d. that is, it is almost only palladium secreted in the resin.

The resin absorbed at pH = 0, almost exclusively the palladium. To obtain the platinum content in the aqueous solution was the pH of the aqueous solution Solution set to 2.5 and the solution with fresh Ion exchange resin P (9) added.

For the recovery of the platinum or palladium content the loaded ion exchangers were concentrated Hydrochloric acid added and stirred for 4 hours. By atomic absorption spectroscopy was found to be an essential Part of the absorbed palladium or platinum had passed into the acidic solution. By evaporation could the palladium or platinum content in pure form  isolated and then in the usual way on pure platinum or pure palladium can be worked up.

Example 7 Use of the ion exchange resins according to the invention for the separation of platinum, palladium and rhodium in aqueous solutions

An aqueous solution containing 525 mg / l Pt ⁴⁺ , 189 mg / l Pd ²⁺ and 150 mg / l Rh ^{3+ was used} . The aqueous solution was acidified by adding hydrochloric acid so that the hydrochloric acid content was 1 mol / l. 20 ml of the hydrochloric acid solution were then removed and placed in a flask with 500 mg of the one in Example 4.2.4. exchange resin P (9) obtained and allowed to stand for 3 days. The palladium-loaded resin was filtered off and worked up as described below. The aqueous solution, which essentially only contained the platinum and rhodium, was adjusted to a pH of 2.5 and mixed with 500 mg of the in Example 4.2.4. exchange resin P (9) obtained. After 3 days, the platinum-loaded resin was filtered off and worked up as described below.

The aqueous solution essentially only contained Rhodium. The rhodium was removed by evaporation from the aqueous Solution isolated and in a known manner on rhodium worked up.

The ion exchange resin loaded with palladium was converted into 30 ml of concentrated hydrochloric acid stirred for 4 hours. The Regenerated resin was filtered off, the palladium content isolated from the hydrochloric acid solution by evaporation and on Palladium worked up. In an analogous way, that was with Platinum-loaded ion exchange resin regenerates and that Platinum won.  

Example 8 Use of the copolymers according to the invention for separating noble metals from heavy metals 8.1.1. Application for the separation of palladium from lead, mercury and cadmium at pH 0

So much was in a 1 molar hydrochloric acid (pH value 0) Potassium hexachloropalladate that dissolved with a solution about 500 mg / l palladium was obtained. In a liter This solution gave 915.4 mg of lead acetate trihydrate, 676.7 mg mercury dichloride and 1185.5 mg cadmium acetate Dissolved dihydrate. This solution, that of simplicity for the sake of being called "Solution I" in the following about 500 mg / l of each metal ion.

20 ml of solution I were mixed with 500 mg of the invention Copolymer P (9) for a period of 48 hours contacted at 20 ° C.

The copolymer was then removed from the aqueous solution separated and the remaining solution by atomic absorption spectroscopy examined. It was found that the palladium was essentially completely absorbed, the heavy metals lead, mercury and cadmium, however at most in traces: The determined values (absorption about 3% by weight of the lead, 1% by weight of the mercury and 4% by weight of the cadmium in the resin) are in the Error range of the measurement method used, that with about 3-5% is accepted.

8.1.2. Application for the separation of palladium from lead, mercury and cadmium at pH 2

20 ml of the in the example 8.1.1. prepared solution I were adjusted to a pH of 2 with sodium hydroxide solution. The The rest of the implementation and analysis is carried out as in 8.1.1. described. Analysis by atomic absorption spectroscopy  revealed that about 4% by weight of the lead, 6% by weight of the mercury and 5% by weight of the cadmium is absorbed in the resin had been.

8.1.3. Application for the separation of palladium from lead, mercury and cadmium at pH 4

20 ml of the in Example 8.1.1. prepared solution I were adjusted to a pH of 4 with sodium hydroxide solution. The the rest of the test was carried out analogously to Example 8.1.1. Analysis by atomic absorption spectroscopy showed that 3% by weight of lead, no mercury and 4% by weight of the cadmium had been absorbed in the resin.

8.2. Application for the separation of palladium from copper, nickel and iron

So much potassium tetrachloropalladate was in one liter of 1 molar hydrochloric acid resolved that a solution with about 500 mg / l palladium was obtained. In this solution 1570.9 mg copper acetate hydrate, 1104.3 mg nickel dichloride and 1452.3 mg iron trichloride dissolved. It was there receive a solution in which each about 500 mg / l of contained in every metal ion. This solution will be the For the sake of simplicity, hereinafter referred to as "Solution II".

8.2.1. Application for the separation of palladium from copper, nickel and iron at pH 0

20 ml of solution II were mixed with 500 mg of the invention Copolymer P (9) for a period of Contacted for 48 hours at 20 ° C (the copolymer was previously swollen in 1 molar hydrochloric acid and then washed neutral). After that, the loaded one Copolymer was separated from the solution containing cations and the remaining solution by atomic absorption spectroscopy examined. The analysis showed that the  Palladium is essentially completely absorbed in the resin had been. Nickel and iron had not been absorbed, only about 3% by weight of the copper (this value lies within the error limit of the measurement method used, which is assumed to be around 3-5%).

8.2.2. Application for the separation of palladium from nickel and iron at pH 2

20 ml of solution II were mixed with sodium hydroxide solution on a pH adjusted to 2. The rest of the experiment was carried out analogously to 8.2.1. Analysis by atomic absorption spectroscopy revealed that the palladium essentially had been completely absorbed. Nickel was also there pH 2 was not absorbed. For iron was one Absorption of 27 wt .-% determined.

The examples 8.1.1. until 8.1.3. and 8.2.1. and 8.2.2. demonstrate the suitability of the copolymers according to the invention for the separation of precious metals such as palladium from Heavy metals such as lead, mercury, cadmium, nickel and Iron and, at pH = 0, also copper.

8.2.3. Application for the separation of copper from lead, cadmium and mercury

20 ml of a solution adjusted to pH = 2 or pH = 4, the Lead, cadmium, mercury and copper as well as in the case of pH = 4 performed experiment, also nickel, each in a concentration of approx. 500 mg / l each one pre-swollen with 500 mg each in neutral solution Resin P (9). The resin was then filtered and determined the content of the respective solution using AAS. The results are summarized in the table below. It shows the absorbed parts of each Heavy metal. Here is an error of about 1% count.  

It can be seen that the heavy metals lead, cadmium and Only a small amount of mercury is absorbed. At very low pH values, at which preferably at the platinum group metals are separated, they are only absorbed to a small extent. Likewise, Nickel not or very little removed from the aqueous solution. In contrast, copper becomes resin at pH = 2 and pH = 4 absorbed.

Claims (18)

1. Process for the preparation of copolymers containing bisimidazole groups, characterized in that compounds of the general formula (I) wherein
R¹ and R² can be the same or different and R¹ is alkyl with 1 to 3 C atoms, especially methyl, vinyl, linear or branched alkenyl with 3 to 6 C atoms, halogen-substituted alkenyl with 2 to 6 C atoms and R² Means vinyl, linear or branched alkenyl with 3 to 6 C atoms, halogen-substituted alkenyl with 2 to 6 C atoms,
R³ is hydrogen, linear or branched alkyl having 1 to 6 carbon atoms, alkyl substituted by halogen having 1 to 6 carbon atoms, aryl, in particular phenyl, substituted aryl, in particular phenyl substituted by one or more halogen atoms and / or lower alkyl groups, in particular p -Halogenphenyl, tolyl means
copolymerized with ethene derivatives of the general formula (II) wherein
R⁴ alkyl having 1 to 6 C atoms, COR⁸, COOR⁹, CO (NR₂¹⁰), wherein R⁸, R⁹, R¹⁰ are lower alkyl having 1 to 3 C atoms; Aryl, especially phenyl, substituted aryl, preferably phenyl substituted by halogen or lower alkyl, especially p-halophenyl, tolyl; the rest CN means
R⁵, R⁶, R⁷ may be the same or different and are hydrogen, optionally substituted by halogen-substituted lower alkyl having 1 to 3 carbon atoms. 2. The method according to claim 1, characterized in that that one uses compounds of formula (I) in which R¹ and R² are the same or in which R¹ is methyl and R² has the meaning given above. 3. The method according to claim 2, characterized in that R¹ and R² are vinyl. 4. The method according to claim 1, characterized in that R¹ is methyl and R² is vinyl. 5. The method according to claim 1, characterized in that R³ is hydrogen, methyl, ethyl, propyl or phenyl. 6. The method according to claim 1, characterized in that one uses compounds of formula (II) in which  R⁵, R⁶ and R⁷ are hydrogen and R⁴ are phenyl, CN or COOR⁹, wherein R⁹ is methyl or ethyl. 7. The method according to any one of the preceding claims, characterized in that the copolymerization is radical initiated. 8. The method according to any one of the preceding claims, characterized in that the copolymerization in Form of solution, precipitation or suspension polymerization carries out. 9. The method according to any one of the preceding claims, characterized in that the compounds of general Formula (I) and the general formula (II) in Molar ratio from about 1:20 to about 1: 3. 10. The method according to any one of the preceding claims, characterized in that one continues to di- or uses multifunctional crosslinking agent. 11. The method according to any one of the preceding claims, characterized in that the copolymers obtained protonated or quaternized with lower alkyl groups. 12. Copolymers containing bisimidazole groups are available according to a method of claims 1 to 11. 13. Process for the separation of platinum group metals, especially platinum and / or palladium, from aqueous Solutions, whereby an aqueous solution, which Contains platinum group metals with a by a process Bisimidazole groups obtainable according to Claims 1 to 9 containing copolymer under conditions contacted the separation of the platinum group metals enables and the separated platinum group metals wins.   14. Process for the separation of platinum group metals, especially platinum from palladium, platinum from rhodium, Palladium of rhodium or platinum, palladium and rhodium from each other, whereby an aqueous solution, the platinum group metals contains, with one after a procedure of claims 1 to 9 obtainable, containing bisimidazole groups Copolymer contacted under conditions that allow the separation and the separated Platinum group metals wins. 15. The method according to claim 14, characterized in that one for the separation of platinum, palladium and Rhodium from each other in a first step the conditions so that essentially only palladium is absorbed so that in a second step the conditions so chooses that when contacting the aqueous solution, the contains essentially only platinum and rhodium, with fresh copolymer essentially only absorbs platinum and the platinum-loaded copolymer from the aqueous solution, which is essentially only Contains rhodium, and separates them from each other separated metals isolated. 16. The method according to claim 15, characterized in that in the first step at a pH between about 0 and 1 works and in the second step the pH value increased at least 2.5, in particular 2.5 to 7. 17. Process for the separation of precious metals, in particular Platinum and / or palladium of heavy metals, especially lead, mercury, cadmium and / or Nickel, characterized in that an aqueous solution, the precious metals, especially platinum and / or palladium and heavy metals, especially lead, mercury, Contains cadmium and / or nickel, at a pH between about 0 and 4, preferably 0 and about 2, with one bisimidazole groups obtainable by a process of claims 1 to 9 containing copolymer contacted and  the copolymer loaded with the precious metal from the aqueous solution that is essentially only heavy metal contains, separates. 18. Monomers of the general formula (III) wherein
R¹¹ and R¹² may be the same or different and R¹¹ is alkyl with 1 to 3 C atoms, preferably methyl, vinyl, linear or branched alkenyl with 3 to 6 C atoms, halogen-substituted alkenyl with 2 to 6 C atoms and R¹² Means vinyl, linear or branched alkenyl with 3 to 6 C atoms, halogen-substituted alkenyl with 2 to 6 C atoms,
R¹³ is hydrogen, linear or branched alkyl having 1 to 6 carbon atoms, halogen-substituted alkyl having 1 to 6 carbon atoms, aryl, in particular phenyl, substituted aryl, in particular substituted phenyl, preferably p-halophenyl, tolyl.